This invention relates to systems and methods for disinfecting contact lenses. More particularly, the invention relates to systems and methods adapted to simultaneously combine a disinfectant component and a disinfecting destroying or inactivating component so that a contact lens contacted with this combined material is disinfected and can be placed in the eye of a human being for safe and comfortable wear.
Contact lenses should be periodically disinfected by the user to prevent infection or other deleterious effects on ocular health which may be associated with contact lens wear. Currently, there are several different conventional systems and methods which enable the user to disinfect his/her contact lenses between wearing times. These conventional cleaning and disinfection systems can be divided into "hot" and "cold" systems. Hot systems require the use of heat to disinfect the contact lenses, whereas cold systems use chemical disinfectants at ambient temperatures to disinfect the lenses.
Within the realm of cold disinfection systems are hydrogen peroxide disinfection systems. Disinfecting hydrogen peroxide solutions are effective to kill the bacteria and fungi which may contaminate contact lenses. However, residual hydrogen peroxide on a disinfected contact lens may cause irritation, burning or trauma to the eye unless this hydrogen peroxide is destroyed, i.e., decomposed, neutralized, inactivated or chemically reduced. Therefore, destruction of the residual hydrogen peroxide in the liquid medium containing the disinfected contact lens is needed to enable safe and comfortable wear of the disinfected contact lens. Liquid media (not including the hydrogen peroxide contained therein) used to disinfect contact lenses should be substantially isotonic, for example, to the human eye, and preferably ophthalmically acceptable so as to reduce the chances of problems caused by placing the disinfected lenses in the wearer's eyes.
Thus, there are substantial advantages to destroying hydrogen peroxide before placing the treated lens in one's eye.
Conventional hydrogen peroxide disinfection of a contact lens often involves the use of a hydrogen peroxide destroying component (HPDC), such as platinum, secured to a reusable disc or in a sequential process. Platinum-containing discs can degrade and become ineffective with time and repeated use due to adsorbed tear components and oxidation. This ineffectiveness can result in potentially damaging amounts of hydrogen peroxide being introduced into the eyes.
In a typical sequential process, hydrogen peroxide is first used to disinfect the contact lens. Then, after the contact lens has been disinfected, a HPDC is used to destroy the hydrogen peroxide, For example, after contact lens disinfection in a hydrogen peroxide-containing liquid medium (HPLM), a second liquid medium containing a HPDC is added to the HPLM to destroy the hydrogen peroxide. Alternatively, the HPDC can be included in a tablet or pill having a delayed release coating. After the lens is disinfected in the HPLM, the HPDC is released into the HPLM to destroy the hydrogen peroxide.
Such sequential processes are time consuming and involve either two or more steps or a delayed release coating. The multi-step processes adversely effect user compliance. For example, a lens wearer may forget the step to destroy the hydrogen peroxide and place damaging amounts of hydrogen peroxide in the eye. Delayed release coatings, on the other hand, are often at least partially soluble in the HPLM and can be carried with the disinfected lens when the lens is placed in the eye to be worn. Certain wearers may have an actual or perceived sensitivity to such solubilized coatings in the eye.
Therefore, it would be advantageous to provide contact lens disinfection systems and methods which are effective, involve a single step and/or reduce, or even eliminate, the risk of placing hydrogen peroxide in the eyes.